Continuous mining machines typically use conical or point attack bits to remove material. These bits, although inexpensive to produce, require high forces for material excavation that dictate the physical size and power requirements of the mining machine. Also, the mineral material mined by impacting the surface with point attack bits is inherently shattered, reducing a significant portion of the mineral into relatively small pieces and powder. For example, coal mined with point attack bits typically contains 4% to 7% fines which require separation, usually by washing, prior to delivery to an end user. In actual field tests, it was found that 20% to 60% of gypsum mined with point attack bits was reduced to particles having a nominal size of less than 1/4 inch. The large percentage of fine particles plugged conveyors and, when stockpiled during winter months, froze into a solid mass that could not be handled until it thawed the following spring.
The present invention is directed to overcoming the problems set forth above. It is desirable to have a method of mining mineral materials that require lower penetration forces and energy requirements than currently used mining methods. It is also desirable to have a method of mining mineral materials that produces well defined, controllably sized, discrete pieces of the mineral material without significant loss of material in the form of dust, powder or fine particles.